this air bubble theory doesnt sound plausable...

if the coolant isnt circulating due to an airbubble, that engine should be hot no matter what, it should overheat at idle.

further, the heat is driven off the engine coolant, so again if it isnt circulating, turning on the heat should just blow normal air at you.

maybe Im missing something, but Ive never heard of an airbubble only causeing problems at high speeds.

heres a test, you say it happens at 80-100. thats... about 3500RPM? try driving at 40mph in 4th or 5th, whichever gets you closest to 3500rpm, and cruise for a few miles. see if its a speed of the car related problem, or maybe just that you dont cruise at 3500RPMs too often.

 

Ares, the airbubbles and trapped around the cooling system...as the car moves, coreners, etc...they travel and float all over the place. This is what causes the erratic high and low temp conditions. I experience this first hand when I installed my TT. As the engine revs...more demand on the cooling system...more demand on the coolant...which has a bunch of air bubbles in it.

My car was also too warm at idle...in addition to going very hot once cruising.

 

ok here's some more info.. the temp gauge starts going up very soon after i hit 3000 rpm.. i drove it for two hours below 3000 rpm and no problems..

at some point the temperature gauge did go all the way to the top, unfortunatelly i was on the freeway and even the heater wasnt helping.. that happened only once so i dont know if the gaskets got messed up...

once again thanks for so many suggestions...

 

Not to get off topic but is there a chance of air getting into the transmission fluid and is there a relief cap like this for air pockets in the tranny compartment? I just had a converter installed on my automatic Z and was wondering.

 

Same thing happened to me when I drained my radiator fluid. I would only overheat at 3000 rpm or more. My radiator definitely had air in it. I had to release the air by opening the radiator cap when the car cooled off and by opening the relief valve in the back also. I had to do this several times.

 

i just cracked open the air relief valve and hear a bunch of air come out along with some coolant O_o heh.. but yea.. i'm about to drive home.. about 120 miles.. so i'll speed a bit last couple miles to check if i over heat or not.. now i jsut try to go under 3000rpm on the roads.. heh.. anyway.. more results later...

 

The automatic transmission has an "Air Breather Hose". As long as its properly installed and "not crushed or blocked by folding or bending" you should be fine. Any entrained air will work its way out in a couple of days.

How's the new TC working out for you?


DaveO

 

We almost lost an engine due to improper filling of the radiator after it was changed from being damaged by road debris 2 weeks after the wife got the car. Nissan actually has a tool to bleed the cooling system which the dealership let me borrow since it was close to quitting time when we steamed (literally) back to them after picking the car up. Because of the aero-dynamic design, the radiator sits lower than the block making it difficult to purge all the air. Their remedy is a funnel that screws in place of the radiator cap and sits a bit higher than the block. It holds about a half gallon of antifreeze. You screw it in place, fill the funnel, start er up and let the cars cooling system cycle several times. You bleed the initial air out of the heater hose bleed port and the rest will burp thru the funnel. No lie, I used the tool myself since their service manager wouldn't go the extra mile and help us since they were about to close.

 

Nothing like bumping a 6 year old thread lol